million miles, what hillary clinton told andrea mitchell about her recent health scare. >>> a new beginning for a genuine american hero. the wonders of modern medicine giving him a whole new outlook on life. >>> and when to eat. why doctors now say timing is everhinghen it comes to losing weight. nightly news begins now. >>> good evening. we begin tonight with some of the most severe temperature swings that nature is capable of producing on this planet. they are now under way right now across a big part of our country. and as a result, we are also watching some severe weather very closely, things like tornadoes in january. this will give you some idea of what's going on across the country tonight. in denver, temperatures have just fallen 27 degrees in a day. kansas city, 30 degrees colder. cut bank, montana, 40 degrees colder. in chicago, where today, it was 63, by thursday, it will be 18. there is an explanation for all of it, but it is a wild 24 hours. we begin with weather channel meteorologist mike seidel, who is out ahead of some of the violent weather in little rock tonight.